routers

My router has two speeds.   One supports the internet; one supports the security system and cameras.   

Fast speed is for internet; slow one is for surveillance and cameras.   

My security system and cameras can no longer find the slow speed.

When I try to reset the cameras (a process I am familiar and comfortable with), which is a fairly simple, the router no longer shows the slow speed as an option out there in the ether.   I specifically bought this router to support this security system and it has worked fine for years.   Now, all the sudden, only the fast speed is showing up as an option.

Problem #2:   I want to change my password as I am certain someone has hacked my system.   

I am technologically NOT advanced.   

Any assistance or direction to a how-to video would be VERY appreciated.   

I need to fix both problems.   

I need to reset my password.   

I need to make the slow speed findable so I can reconnect my cameras.   

Thanks very much,

Matt